Traditionally, the chain guard of a bicycle has been fitted by bending a thin metal sheet under pressure and locking the sheet at the ends thereof in front and in back by means of locking bolts concurrent with the locking of the chain guard. The disadvantages of such fitting include the need for repeated fastening of the guard with a screwdriver; much manual labor; much manipulation in the placing, aligning, and pressing; the need for additional bolt lockings, holding of the chain guard, etc. All of this is troublesome, and the metal tools and fittings used in the working thereof will easily scratch the bicycle tube, removing the paint therefrom. Additionally, because the thin metal items have a high plasticity but lack elasticity, the metal items, upon being subjected to repeated mounting and dismounting, will fail to match as they should, and will come out of alignment. Still worse is that, in cases in which the fasteners are deformed in some way when they are meant to serve a locking purpose, they will defeat attempts to accomplish the work involved. These disadvantages result from the inferiority of the traditional fasteners for repeated use and their incompatibility for operation with associated parts and components.